The invention relates to the lighting technology sector: in particular, the invention concerns a LED floodlight that can be used above all for road lighting, or for lighting outdoor environments, or large indoor spaces.
LED floodlights used for this purpose are already known, comprising an opaque box-like containment element with a substantially spherical cup shape, a plurality of LED assemblies housed within said box-like element and linearly arranged on a plurality of circuit boards with a tape-like conformation, applied to metallic support strips joined at the top of said spherical cup, a closing optical screen for said box-like element made of transparent material, and an electrical power supply unit for said LEDs suitably connected by wires to the electrical control circuits of each tape-like board.
The LEDs used in said floodlights may indifferently emit white or coloured light, or be RGB type LEDs, and, in order to increase the luminous effect, they are often associated singly with a known type of lens, smooth or bossed, with a known property of concentrating or scattering the beams of light coming from a luminous source.
Also said closing optical screen has a smooth or machined surface with suitable bosses of different sizes, for further modulation of the light produced by all the LEDs.
This type of LED floodlight has certain limits and disadvantages.
The presence of a given structure constituted of tape-like boards on which the LEDs are positioned, applied to support strips, greatly conditions the distribution of the light sources, creating certain zones with a greater density of lighting power, and other zones with a lower specific lighting power. In fact, the strips inevitably cause a greater density of LEDs in the centre of the spherical cup and fewer LEDs towards the periphery. To ensure that the whole floodlight produces a uniform lighting effect, it is necessary to alternate, and carefully position on said support strips, LEDs with different lighting powers. Sometimes it may also be necessary to select only some LED assemblies to be supplied with, while others are kept switched off. This aim is achieved by means of a complex electrical control circuit, and a plurality of electrical cables.
Disadvantageously, the use of LEDs with different lighting power and the determination of their exact position, the use of several mechanical components for fastening said tape-like boards to the support strips and for joining the latter to the box-like element, and the use of electrical power supply and control cables and components for switching on each individual LED, greatly increase the time and costs involved in the construction of the floodlight, and maintenance costs when using the floodlight.
Furthermore, the presence of numerous electrical components increases the risk of short circuits and reduces the life-time of the appliance.
Lastly, the space inside the box-like element delimited by the closing optical screen, wherein the support strips for the LEDs are contained, disadvantageously retains a considerable concentration of heat, which is difficult to dissipate. To ensure lower temperatures inside said box-like element it is therefore necessary to use a smaller number of LEDs, or LEDs with lower light-emitting power, disadvantageously resulting however in a weaker light yield.